Upon asphalting of a surface, homogeneousness is important, since it is the worst parts that initiate maintenance measures. In practice, it is impossible to improve the quality of an asphalt pavement at ambient temperature. Thermographic photographing reveals segregation problems, which may be caused by the asphalt plant, the transport of the asphalt out on the road, or practical measures in connection to the change from one lorry batch to the next one. Measured results can be used for improvements in the asphalt plant or to revised routines. Results from thermographic measurements can lead to a reward or reduced remuneration for the asphalt laying carried out.
U.S. Pat. No. 6,122,601 (Swanson et al.) discloses a compacted material density measurement and compaction tracking system, namely a two component system to obtain uniform density of compacted materials and track the compaction of the materials. The first component provides an automated, real-time compaction density meter and method of use to measure the density of the compacted material. The second component provides a Geographic Information System (GIS) for tracking compaction of a surface at specific locations. The two components of the present invention combined provide a system to measure the density of the compacted material and record the location of each density measurement. The components of the present invention can be utilized for many compaction operations, such as the roller compaction of concrete, pavement, soil, landfills, and asphalt pavements.
A CDS (Compaction Documentation System) was developed in the mid-'80s in Sweden (The Geodynamic Compaction Documentation System. Sweden: GEODYN, Inc., 1995). This CDS provides a conceptual system to monitor the compaction process. In this system, the operator enters the compaction data manually when he operates the compactor. All records, including lane change, direction change, number of passes, layer number, and start or stop to operate must be entered by hand. Moreover, there was no sensor to identify the orientation and position of moving compaction equipment, so operators must follow the moving path that was decided previously.
The technology of automated real-time positioning has improved tremendously in the last few years. Currently, there are two main modes for positioning, laser and GPS. Laser positioning is extremely accurate (<10 cm), however, it is limited by the need to place multiple laser targets that act as receivers. GPS is a satellite based technology. It is relatively inexpensive however accuracy is typically 3-5 meters, which is insufficient for this research. Through the use of differential GPS, the accuracy is improved to <1 m which is still unacceptable. However, with the application of software corrections, GPS differential measurements (GNSS) can have an accuracy of <10 cm.
Further, US 2014/0308074 (Rutz et al.) discloses a road finishing machine with a thermographic device releasably fixed to a portion of the machine for recording a georeferenced thermographic data record of at least one region of a pavement layer. The thermographic device includes a housing in which a detection unit for detecting a thermographic data record and a further detection unit for detecting a space-related data record for the thermographic data record are disposed.
In none of the known methods there is given any reliable quality measurement that preferably may easily be related to the actual lifetime of a newly laid asphalt pave.